li=[7,6,5,4,3,2,1,11,12]
leng=len(li)
mid=li[leng//2]
left=[]
right=[]
mide=[]
for index in range(0,leng):
    if li[index]<mid:
        left.insert(li[index])
    elif li[index]>mid:
        right.insert(li[index])
    elif li[index]==mid:
        mide.insert(li[index])
